The present invention relates to an analytical element and a method for use in trace analysis of a fluid sample, and more particularly to an analytical element for use in the analysis of a specific microconstituent of a biological fluid sample.
Various analytical methods have been developed as the method for detecting microconstituents contained in biological fluid samples. Such analytical methods are based basically on the principle of immune reactions. Various measuring methods have been developed to date as ones using the above principle, and among these the immunity measuring method is known as the best accurate one.
As the immunity measuring method, the radiation immunity measuring method has been extensively used since when Berson and Yallow succeeded in measuring the insulin in a serum by using bovine insulin and the antiinsulin antibody in the serum of a diabetic labeled with radioactive iodide.
Since then, various materials other than radioactive isotopes as the labeled compound have been developed so far. Such various other compounds include, for example, enzymes, enzyme substrates, coenzymes, enzyme inhibitors, bacteriophages, circulation reactants, metals and ogranic-metallic complexes, organic prosthetic groups, chemical emission reactants, fluorescent moleculars, etc.
One of the important technical problems on the above immunity measuring method is the separation (hereinafter abbreviated to B/F separation) between the combined material (hereinafter abbreviated to B) and uncombined material (hereinafter abbreviated to F).
In order to solve problems in the immunity measuring method, various methods have hitherto been developed as disclosed in. e.g.. Japanese Patent Publication Open to Public Inspection (hereinafter referred to as Japanese Patent O.P.I. Publication) Nos. 38619/1978, 79024/1983, 90859/1980, 67860/1982, 200862/1982, 18167/1983, 77356/1984 and 170768/1984.
These methods, however, are disadvantageous in respect that, in these methods, the B/F separation is inadequate; there are questions in the signal's reliability because of many noises; measurable materials are limited to low-molecular materials only; and the like.